The mechanical and inflammatory low back pain (MIL) index: development and validation

Cuesta-Vargas, Antonio, Farasyn, Andre, Gabel, Charles Philip, & Luciano, Juan V. (2014) The mechanical and inflammatory low back pain (MIL) index: development and validation. BMC Musculoskeletal Disorders, 15, Article number-12.

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  • The purpose of this study was the development of a valid and reliable “Mechanical and Inflammatory Low Back Pain Index” (MIL) for assessment of non-specific low back pain (NSLBP). This 7-item tool assists practitioners in determining whether symptoms are predominantly mechanical or inflammatory.


  • Participants (n = 170, 96 females, age = 38 ± 14 years-old) with NSLP were referred to two Spanish physiotherapy clinics and completed the MIL and the following measures: the Roland Morris Questionnaire (RMQ), SF-12 and “Backache Index” (BAI) physical assessment test. For test-retest reliability, 37 consecutive patients were assessed at baseline and three days later during a non-treatment period. Face and content validity, practical characteristics, factor analysis, internal consistency, discriminant validity and convergent validity were assessed from the full sample.


  • A total of 27 potential items that had been identified for inclusion were subsequently reduced to 11 by an expert panel. Four items were then removed due to cross-loading under confirmatory factor analysis where a two-factor model yielded a good fit to the data (χ2 = 14.80, df = 13, p = 0.37, CFI = 0.98, and RMSEA = 0.029). The internal consistency was moderate (α = 0.68 for MLBP; 0.72 for ILBP), test-retest reliability high (ICC = 0.91; 95%CI = 0.88-0.93) and discriminant validity good for either MLBP (AUC = 0.74) and ILBP (AUC = 0.92). Convergent validity was demonstrated through similar but weak correlations between the ILBP and both the RMQ and BAI (r = 0.34, p < 0.001) and the MLBP and BAI (r = 0.38, p < 0.001).


  • The MIL is a valid and reliable clinical tool for patients with NSLBP that discriminates between mechanical and inflammatory LBP.

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ID Code: 82209
Item Type: Journal Article
Refereed: Yes
Keywords: Low back pain; Psychometrics properties; Pain measurement; Screening tool; Inflammatory; Mechanical
DOI: 10.1186/1471-2474-15-12
ISSN: 1471-2474
Divisions: Current > Schools > School of Clinical Sciences
Current > QUT Faculties and Divisions > Faculty of Health
Copyright Owner: 2014 The authors; licensee BioMed Central Ltd.
Copyright Statement: 014 Cuesta-Vargas et al.; This is an open access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestrict
Deposited On: 04 Mar 2015 07:33
Last Modified: 21 Nov 2016 04:37

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